I've come to embrace the notion that I haven't done enough in my life. I've come to confirm that one's title, even a title like president of the United States, says very little about how well one's life has been led. No matter how much you've done or how successful you've been, there's always more to do, always more to learn, and always more to achieve.
The leaders we revere and the businesses that last are generally not the result of a narrow pursuit of popularity or personal advancement, but of devotion to some bigger purpose. That's the hallmark of real success. The other trapping of success might be the by product of this larger mission, but it can't be the central thing.
When nature removes a great man, people explore the horizon for a successor; but none comes, and none will. His class is extinguished with him. In some other and quite different field, the next man will appear.